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Mammograms Are ‘Over-Estimated’

Breast cancer remains the most feared cancer among women, and while doctors recommend mammograms for screening and diagnosis, a new study shows that widespread screening doesn’t necessarily lower the overall death rate from breast cancer or even cut back on the number of biggest breast tumors found later.

The team studied 16 million women aged 40 who were included in a cancer registry covering 547 U.S. counties. They included women who got mammograms. In the year 2000, 53,207 of the women were diagnosed with breast cancer. The researchers followed up for 10 years.

“An absolute increase of 10 percentage points in the extent of screening was accompanied by 16 percent more breast cancer diagnoses but no significant change in breast cancer deaths,” the team wrote in the Journal of the American Medical Association’s JAMA Internal Medicine.

“We did not find any significant change in breast cancer deaths,” Harding said. “This was quite surprising to me,” he added. “I think this tells us that the potential of overdiagnosis is high.”

“We found that countries with the most screening had substantially more breast cancers being diagnosed,” said Charles Harding, a Seattle data analyst who worked with a team at Harvard and Dartmouth universities on the study.

Overdiagnosis means women were diagnosed with and almost certainly treated for tumors that never would have bothered them or caused symptoms during their lives.

“We increasingly realize that in clinical medicine, the more we look, the more we find,” said Dr. Joann Elmore of the University of Washington, who wrote a commentary on the findings.

“So this study is not surprising.”

The topic is under hot debate for the moment. The idea is, of course, to catch cancer early, when it’s easiest to cure. However, even experts do not agree on how early is too early. The American Cancer Society says women over 40 should get a mammogram every year. The U.S. Preventive Services Task Force, which advises the federal government, says women over 50 should get a mammogram every other year. It says women 40 to 49 should decide what they want, based on their health history, and it’s not clear if women over 75 should bother with mammograms.

In 2014, Canadian researchers found 22 percent of the women screened got diagnosed with cancers that would never have harmed them. In 2012, a study published in the New England Journal of Medicine found that as many as a third of cancers detected through routine mammograms may not be life-threatening. It said 1 million women may have been overdiagnosed.

What exactly is Breast Cancer, in a nutshell?

Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, fluid coming from the nipple, or a red scaly patch of skin. In those with distant spread of the disease, there may be bone pain, swollen lymph nodes, shortness of breath, or yellow skin.

Risk factors for developing breast cancer include: female sex, obesity, lack of physical exercise, drinking alcohol, hormone replacement therapy during menopause, ionizing radiation, early age at first menstruation, having children late or not at all, and older age. About 5–10% of cases are due to genes inherited from a person’s parents, including BRCA1 and BRCA2 among others.